There is a growing and consistent need in the concrete construction industry for increased quality close-tolerance, flat and level concrete floors and slabs whereby the finished working surfaces of the floors and slabs being constructed are as flat and level as is economically possible using typical construction methods and finishing procedures. A variety of buildings and structures having concrete floors and slabs-on-grade, as well as elevated multi-level buildings or structures can benefit from achieving an increased smoothness and levelness concrete floor quality specification at a relative minimal increase in labor and cost to the building contractor and the customer.
Concrete floors are specified, measured and compared within the concrete industry according to an accepted concrete floor profile specification and measurement standard. One of these specification standards is for floor flatness “FF” and another is for floor levelness “FL”. These two specifications together are generally known and referred to within the concrete industry as the F-number system. The F-number system offers a repeatable method for measuring floor quality through statistical means known in the art. Further information about this system of measurement as can be found in published documents by the American Concrete Instituted (ACI) under ACI 117, “Tolerances for Concrete Construction and Material”; ACI 302, “Guide for Concrete Floors and Slab Construction”; and ASTM (American Society for Testing and Materials) E-1115 “Test Methods for Determining Floor Flatness Using the F-Number System”, where the details of each are incorporated herein by reference. For example, concrete floor surfaces having floor flatness specifications (FF) of between FF 15 and FF 25 and a floor levelness specification (FL) of between FL 15 and FL 25 are typical of hand screeded and finished concrete using typical manual hand tools and methods. At an increased level of floor flatness (FF) and floor levelness (FL), specifications between FF 50 and FF 80 and a floor levelness (FL) specification of between FL 50 and FL 80 are typical of close-tolerance upper-level-of-quality floors that are often desired in many building or structural applications but may not be especially easy or inexpensive to achieve. At an even higher level on the scale of quality, floor flatness (FF) specifications of between FF 80 and FF 100 and a floor levelness (FL) specification of between FL 80 and FL 100 are typical of very close-tolerance high-quality concrete floors and surfaces. These are often referred to in the industry as “super-flat floors” or simply “super flats”. The equipment and methods used to achieve the higher and highest levels of quality may be typical of using automated laser-guided concrete screeding machines, such as the Somero LASER SCREED™ machines, such as described in U.S. Pat. Nos. 4,655,633; 4,939,935; 6,976,805; and 6,953,304 (which are hereby incorporated herein by reference in their entireties) and manufactured by Somero Enterprises of Houghton, Mich., USA, and in addition with considerable, effort, labor and skill necessary during the final concrete surface finishing operations.
High quality and super-flat concrete floors are typically much more difficult and expensive to consistently achieve than those conventionally produced. In order to achieve a higher level quality leading up to and including super-flat floors, work crews must be skilled, along with substantial level of experience and/or a high degree of training, and special equipment is often used to get the desired results. Placement and striking-off of uncured concrete to a specified grade for a conventional concrete floor or surface can be performed using hand tools; however, laser-guided machines are preferred since they are faster and much more accurate. Other special application tools and equipment, such as highway straight edges, power trowels, pan machines and double trowels, may be used separately, at the same time, or in combination with one another, during the various steps of the finishing process. A relatively large number of skilled workers are required to accurately finish a large floor for example, and production speed of the floor can be relatively slow with conventional processes, tools, and equipment. Additionally, as skilled workers and operators continue to work with the manual tools and finishing machine devices, such as hand and powered concrete trowels, pan machines and scrapers, for a long period of time, the laborers will tend to tire and fatigue as the job progresses, which can have an adverse affect on the final F-numbers and level of quality of the concrete floor or surface.
Some concrete leveling applications have implemented a spinning tube apparatus or the like, for constructing a concrete floors and surfaces. However, such spinning tube applications are typically implemented as an initial strike-off tool, such as a screed for striking-off or screeding freshly placed and uncured concrete to the desired grade. These tube type roller screeds are necessarily supported on some type of preset forms or screed rails to maintain grade height. Because these screeding devices are applicable only to freshly poured, uncured concrete, and the use of accurately set forms or guide rails implementation of such devices does not easily result in a close-tolerance or super-flat concrete floor surface. The additional manual processes still have to be performed on the surface after the initial screeding operation is completed, and after the concrete is at least partially set-up and beginning to cure, in order to obtain such a high quality or that approaching a super-flat concrete floor surface.
For the purposes of reference, a concrete machine and method for smoothing and flattening partially cured concrete to a close-tolerance surface that uses spinning rollers is disclosed in U.S. Pat. No. 6,695,532, issued Feb. 24, 2004 to Somero et al. This machine incorporates a movable unit which is movable and supportable over partially cured concrete and is generally supported by wheels or tracks upon the surface of the partially-cured concrete. Two cylindrical and rotatable finishing members or rollers having a longitudinal axis are attached to opposite ends of the machine and used to engage the surface of the partially-cured concrete. The elevations of the each of the cylindrical finishing rollers are adjustable and are controlled by a laser control system. The cylindrical finishing rollers are able to be rotated opposite to the direction of travel of the machine as the unit moves in a first or second direction of travel.
Therefore, there is a need in the industry to increase flatness and levelness quality, while reducing time, effort, cost and necessary skill levels required for creating and finishing high quality concrete surfaces with typically known concrete related procedures and methods.